A probe card is used as a signal transmission interface between a tester and a device under test. In order to efficiently transmit high-frequency test signals, the impedance value of the probe card must be identical or similar to that of the tester and the device under test (DUT).
A plurality of known conventional methods is used to achieve the above purpose. For example, the quantity of conductive soldered joints in the probe card are changed that can make the impedance value of the probe card identical or similar to that of the tester and the DUT. As another example, the probe card with a plurality of coaxial probes can improve electrical transmission capacity by lowering the parasitic capacitance between the coaxial probes. In yet another example, the impedance value of the probe card is adjusted to be consistent with that of the tester and the DUT by exchanging/swapping electronic components with different impedance value.
The above described method could help in achieving the above purpose, but leave much to be desired. For instance, in the exchanging or swapping process of electronic components, the electronic component (e.g. an. inductor) is directly welded with the conductive contact pad so as to be electrically connected. Therefore, when the measured impedance value of the probe card is not close to that of the tester and the DUT, and is higher than a predetermined value, the solder must be removed before the electronic component is taken off, and followed by welding a new electronic component having a different impedance value on the probe card for completing the exchanging/swapping process of the electronic components.
However, in the operations for removing solder and for welding electronic component, the operational difficulties leads to the exchanging/swapping process to become more burdensome thereby lowering the efficiency of the electrical testing. In addition, in the process of mounting the new electronic component, the aligning of the tiny electronic component with the conductive contact pad on the printed circuit board is not an easy task, and thus making more difficult on the exchanging/swapping process. Furthermore, the electronic component is prone to be damaged during the solder removing and welding procedures. Therefore, due to the operational difficulties and the desire for efficient electrical testing, there is still room for improvement in matching the impedance value of the probe card with that of the tester and the DUT by exchanging/swapping the electronic components.